Recently years, flat sensor modules or so-called touchpanels used for detecting a finger touch position are applied to home electrical appliances including OA appliances. In an electronic device having a touchpanel function, it is studied to add the touchpanel function by separately attaching a touchpanel board to a display device such as a liquid crystal display device or organic electroluminescent display device.
A resistance-type touchpanel can extract positional information of a portion touched (depressed) by a finger by arranging mechanical switches at respective intersections of wirings arranged in a matrix form, sequentially applying pulse voltages to address lines, measuring a potential variation of a signal line at desired time and processing a signal. Further, a capacitance-type touchpanel can extract positional information of a portion touched by an input unit by deriving a variation in the capacitance between a detection electrode and a finger.